Vascular sheaths and guide catheters are used routinely in interventional radiology and interventional cardiology. The sheath serves as a conduit from the skin surface to the artery to allow passages of catheters, guide wires, stents, angioplasty balloons and similar instruments through the subcutaneous track without damaging the surrounding tissues or the blood vessel itself. The sheath is generally composed of four main components. The first is the tubular portion, which is the conduit from the skin surface into the blood vessel. The second portion is a hemostatic valve on the skin surface portion of the sheath. The third component is a sidearm tubing with a stopcock that allows the sheath to be flushed or aspirated with fluid. The fourth component is a tapered dilator that passes through the tubular portion of the sheath to allow a non-traumatic introduction of the sheath into the blood vessel. Once the sheath is introduced into the blood vessel, the dilator is then removed to allow passages of catheters. These sheaths are used in over 99 percent of all vascular cases. The vascular sheaths are generally used by first puncturing the blood vessel with a needle, followed by insertion of a guide wire. A dilator, having mounted in the vascular sheath, is then advanced into the blood vessel over the guide wire. The dilator is removed, leaving the distal end of the vascular sheath inside the blood vessel.
While these current vascular sheaths and methods are generally suitable, they have many drawbacks.
The designs of current vascular sheaths do not adequately maintain the sheaths steadily in the blood vessel. For example the sheaths can be easily pulled out of the blood vessel during manipulations of catheters and other devices within the lumen of the sheath.
Further, when using vascular sheaths to perform surgery on carotid artery stenosis, emboli may form during the course of the procedure. These emboli can flow into the cerebral vasculature, leading to ischemic stroke. Current sheaths do not adequately prevent the flow of emboli into the cerebral vasculature.
Still further, during a number of vascular procedures, it would be advantageous to reposition the sheath from a retrograde position (against the blood flow) to an antegrade position (with the blood flow) or visa-versa. For example, when placing a stent in a vessel, performing an angioplasty or performing a thrombectomy, a vascular sheath is inserted to the treatment location using a retrograde common femoral arterial approach. However, during such procedures, it is often discovered that there are a plurality of treatment locations. For example, in performing an angioplasty procedure on an obstructed vessel, it is not uncommon to find that the vessel is obstructed at more than one location. For example, one location may be located upstream from the insertion point of the vascular sheath and another location may be located downstream from the insertion point of the vascular sheath. Thus, it would be very desirable to be able to position the vascular sheath in a retrograde position to treat the first location, followed by repositioning of the vascular sheath in an antegrade position to treat the second location. This is extremely difficult to do with the current sheath technology. These sheaths pull out of the vessel when the operator tries to redirect the sheath, and the operator loses vascular access. Thus, with current sheath designs, the first location is first treated by making an incision to provide retrograde access to the first obstructed location. After the first location is treated, the sheath is removed and the puncture in the vessel must be allowed to heal prior to treatment of the second obstructed location. It can take as long as a week for the puncture in the vessel to heal. The patient must then return for a second procedure to treat the second obstructed location, which requires a second incision.
Additionally, current methods for Fogarty balloon thrombectomy require a surgical incision of the blood vessel and clamping of the blood vessel distal to the incision (for an iliac artery thrombectomy). The balloon is passed to the superior most aspect of the clot, inflated and pulled inferiorly, dragging the clot to the arteriotomy site and out of the blood vessel. If the same aforementioned procedure were performed percutaneous with current sheath technology, the size mis-match between the blood vessel and the sheath would cause the clot to flow past the sheath and into the distal blood vessels.
Thus, any improvements in vascular sheaths would be desirable.